Subtalar Joint

Question 1

What is the STJ?

Answer 1

articulation between talus and calcaneus

Question 2

what is the function of the STJ?

Answer 2

allows for shock absorption during gait

Question 3

what is the function of interosseous talocalcaneal ligament?

Answer 3

limits inversion and eversion (but mostly eversion)

Question 4

which ligament limits inversion? which ligament limits eversion?

Answer 4

cervical ligament- limits inversion

interosseous ligament- limits eversion

Question 5

what is the STJ axis?

Answer 5

42 degrees from transverse plane

16 degrees from sagittal plane

Question 6

what is the primary motion of STJ?

Answer 6

almost equal ratio of inversion- eversion to abduction: adduction (because there is equal movements for frontal and transverse planes)
*very little sagittal plane motion (dorsiflexion/plantarflexion)

Question 7

what is the ratio for transverse and frontal: sagittal plane motion for STJ?

Answer 7

3:1 ratio

Question 8

in OKC, describe what is happening in supination

Answer 8

inversion, plantarflexion and adduction

Question 9

in OKC, describe what is happening in pronation.

Answer 9

eversion, dorsiflexion, and abduction

Question 10

what is the STJ doing during 1st half of OKC?

Answer 10

STJ pronates during 1st half of OKC. this allows for ground clearance

Question 11

what is the STJ doing during the last half of OKC?

Answer 11

STJ starts to supinate

just before heel strike though, the STJ is in neutral

Question 12

at heel strike, what is the STJ doing?

Answer 12

STJ is supinated (but moving towards pronation)

Question 13

in CKC, what is happening in supination? (in terms of calcaneus, talus, and tibia)

Answer 13

calcaneus inverting
talar head is abducted and dorsiflexed
tibia is externally rotating

Question 14

in CKC, what is happening in pronation? (in terms of calcaneus, talus, and tibia)

Answer 14

calcaneal eversion
talar head adduction and plantarflexion
tibia internal rotation

Question 15

what relationship does talus have to the leg?

Answer 15

talus acts as an extension fo the leg and will follow its motion
Ex. internal leg rotation- talar adduction
Ex. external leg rotation- talar abduction

Question 16

what relationship does talus and leg have to the calcaneus?

Answer 16

because talus and leg are proximal to axis, will act in OPPOSITE motion of the calcaneus

Question 17

in CKC, what happens to STJ at heel strike?

Answer 17

at heel strike, STJ is supinated but quickly starts to pronate. (which unlocks the rest of the joints in the foot)This allows foot to become a “mobile adaptor” and allows for shock absorption.

Question 18

in CKC, during midstance, what happens to STJ?

Answer 18

during midstance, STJ starts to supinate to allow for heel-off . Foot becomes a rigid lever.

Question 19

in CKC, what is STJ pronation good for?

Answer 19

shock absorption (esp when foot strikes the ground)

Question 20

in CKC, what is STJ supination good for?

Answer 20

allows foot to become a rigid lever to propulse off the ground

Question 21

what is the STJ total ROM?

Answer 21

(30 degrees total ROM)

2:1 ratio of supination (calcaneal inversion) to pronation (calcaneal eversion)

Question 22

what is the max. degrees of STJ inversion/ eversion?

Answer 22

(2:1 ratio)
inversion- 20 degrees
eversion- 10 degrees

Question 23

how do you calculate STJ neutral thru ROM?

Answer 23

max. eversion - (inversion + eversion/3)

* determine which direction (varus/valgus) based on the normal STJ ROM (inversion- 20, eversion- 10)

Question 24

how do you measure STJ neutral?

Answer 24

1. place patient in prone position
2. bisect calcaneus and lower leg
3. place patient in STJ neutral and measure angle

Question 25

what is the Kirby method used for?

Answer 25

to map out deviated STJ axis

Question 26

where does the normal STJ axis pass through in the foot?

Answer 26

posterior-lateral heel posteriorly and thru the 1st intermetatarsal space of the plantar foot anteriorly

Question 27

if the STJ axis is deviated medially, what does this indicate?

Answer 27

STJ pronation

Question 28

if the STJ axis is deviated laterally, what does this indicate?

Answer 28

STJ supination

Question 29

what happens when you apply thumb pressure medial to the STJ axis?

Answer 29

STJ supination

Question 30

what happens when you apply thumb pressure lateral to the STJ axis?

Answer 30

STJ pronation

Question 31

what is RCSP?

Answer 31

(relaxed calcaneal stance position) - is the position of STJ (calcaneus) when patient is fully compensated in midstance

Question 32

how do you measure RCSP?

Answer 32

1. bisect calcaneus 2. have patient stand and march in place to get them into angle and base of gait 3. mesure calcaneal bisection in relation to WB surface

Question 33

what is normal RCSP?

Answer 33

2 degrees varus to 2 degress valgus

Question 34

how would you compensate for a rearfoot varus (inversion)?

Answer 34

calcaneus will be vertical if fully compensated

Question 35

how would you compensate for a rearfoot valgus (eversion)?

Answer 35

- if neutral position >2 but <10 degrees, the foot will pronate to max. ROM - if over 10 degrees, then talar head hits ground and prevents further pronation

Question 36

what is NCSP?

Answer 36

(neutral calcaneal stance position)- position fo the STJ when patient is placed in neutral posiiton while standing

Question 37

how would you measure NCSP?

Answer 37

1. bisect calcaneus 2. place patient in angle and base of gait. 3. have patient slowly invert/evert foot until neutral talus is palpated. 4. have patient hold position 5. measure calcaneal bisection in relation to WB surface

Question 38

what is the normal tibial influence?

Answer 38

0-4 degrees of varus | *valgus is very unusual unless trauma or congenital abnormality

Question 39

what is tibial influence (tibial stance position)?

Answer 39

bisection of lower leg (tibia) in relation to the ground while in NCSP

Question 40

how could you calculate NCSP?

Answer 40

add amt of tibial influence + STJ neutral